HCA is decided record-wise. If I'm not mistaken, in 2003, Dallas was #3 and Sacramento was #2 but Dallas had the best record and HCA in the WCSF.
Seeding only decides your opponent for the first round and bracket throughout the playoffs.
And if you want to seee the complete aberration of this seeding system, had the #7 Lakers and #3 Nuggets advanced to the second round, the Lakers would have HCA. Adnd if I'm not mistaken, had the Nuggets played the #8 Kings in the conference Finals, the Kings would have HCA.
Yes, a #8 seed would have had HCA in the playoffs against a team in its own conference.